Clarification and demineralization process for b-molasses and similar materials containing concentrated impurities



Jan. 13, 1959 E. w. KOPKE 2,863,677

CLARIFICATION AND DEMINERALIZATION PROCESS FOR B-MOLASSES AND SIMILARMATERIALS CONTAINING CONCENTRATED IMPURITIES 3 Sheets-Sheet 1 Filed July30, 1956 Clarification (See H62) HMIIHFHW Dem/nerafl'zahbn {ii/$eeF/6.4)

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A-Mo/asses Contaminated "5 'Mo/asses IN V EN TOR.

Ems) I V. Kop/re-v BY his affomeys MAJ.

Jan. 13, 1959 E. w. KOPKE 2,868,677

, CLARIFICATION AND DEMINERALIZATION PROCESS FOR BMOLASSES AND SIMILARMATERIALS CONTAINING CONCENTRATED IMPURITIES Filed July so, 1956 A 3Sheets-Sheet 2 mmvron.

Err/sf W Kop/re BY his attorneys Jan. 13, 1959 v E. w. KOPKE 2,86 77CLARIFICATION AND DEMINERALIZATION PROCESS FOR B-MOLASSES AND SIMILARMATERIALS CONTAINING CONCENTRATED IMPURITIES Filed July so. 1956 3Sheets-Sheet 3 WATER SALT SOLUTION a 90 A l P l CLARIFIED HOT WATER SALTSOLUTION MOLASSES V SUPPLY TANK PP Y T SUPPLY TANK 62 STEAM 5 I STEAMTRAP 7 AIR PRESSURE LINE I l 70 g 1 I 72 o.. l

R ECYCLE DEMINERALIZED EXCLUDED LIQUOR LIQUOR LIQUOR INVENTOR. Ernst WKop/re BY his 'affomeys 1i ted States Patent 2,868,677 Patented- Jan.13-, 1 959 Ernst W. Kopke, New York, N. Y.,. assignorto Ultra- SucroCompany, New York; N. Y., a partnership Application July 30, 1956,Serial No. 600,778 11 Claims. (Cl.127-46) This invention relates toprocesses of manufacturing sugar and more especially to the.clarification and demineralization of sugar solutions so. as to.overcome restrictions existing in sugarfactories, especially but notexclusively in raw sugar factories. They also exist in beet sugarmanufactureto extents and degrees whichdiffer due to the diiference inthe amounts and kinds of impurities in beets as compared with cane.

The restrictions lower considerably the yield of'sugar from the rawmaterial.

Also, these restrictions have resulted in molasses which containbacterial and other impurities that restrict the use ofmolasses.

Moreover, the impurities themselves'while undesirable in the sugar andmolasses have longbeen known to be useful; but their usefulness has beenlimited because of the inability to effectively separate them from. themolasses.

Reverting to the matter of increasing sugar yields, various mineralsalts which are present always in considerable amounts in sugar liquors(generally referred to as ash forming material) exert a restrictiveeffect. on finalstage crystallization of sugar from the solutiom Thatgains in sugar yields are attainable through the removal of mineralsalts has been abundantly provedinoperations of various sorts in bothbeet and cane sugar production. However, demineralization, as usuallypracticed, has been costly, chiefly because of the need for regenerantssuch as caustic soda and acid when the. removal of mineral salts isaccomplished by means of ion exchange. Therefore, commercial adaptationshave not proceeded as rapidly as the'attainable, and proved, gainsin'sugar yield would appear to warrant. The'mode of incorporatingdemineralization according, to my present process involves distincteconomies as well as functionaladvantages, particularly in: the finalstages of crystalliza-- tion, and results in substantial economicbenefits.

One objectiveof my process" is toipjrovide for clarificationanddemineralization ofsugar' bearing solutionsatuav processing stage wherethe maximum gain in increased yield ofsugar, purer molasses andseparation of the impurities from the molasses is accomplished atminimunr cost in equipment and in operation.

Another objective is to incorporatca clarification and demineralizationprocess in raw cane sugar factories in the molasses and sugar withseparate collection thereof, and increasing the capacity of existingfinal stage equipment such as vacuum pans, crystallizers andcentrifugals.

Other objects and advantages will become apparent as the inventionisdescribed in connection with the drawings.

In the drawings:

Fig. 1 is a flow diagram of a raw' cane sugar manufacturing process inwhich is incorporated a clarification and a demineralization stageaccording to the present process.

Fig. 2 is a detailed flow diagram of the clarification stage.

Fig. 3 is a fragmentary sectional view of a centrifugal separator bowl.

Fig. 4 is a detailed flow diagram of the demineralization stage.

Accomplishment ofthe above-mentioned objectives by: my inventioninvolves, primarily:

(1) Clarification and demineralization of B mo lasses or any othermolasses or syrup just before itisto be subjected to-final vacuum panboiling and crystalliza-- tion.

-(2) Employment of anion exclusion facility which utilizes a singleresin. bed to remove mineral salts and other non-sugars while retainingwithin the resin bed, the sucrose solute which is thenremoved bywaterrinse, avoiding therebythe use of costly regenerants.

(3 Employment of a step or series of steps which in-- sures and'safeguards the production of raw sugar from cane in areas whereadherence to the. raw sugar standard-- of production is commerciallydesirable.

Thousands ofcycles of successful and-- economical de mineralization ofclarified molasses inaccordance with-my invention have proved" thedependability, high efiicieney and economy ofthe principle of removing.the mineral salts by ion exclusion. Major economies. in equipment andoperation, whichare unattainablewhen using ,ion-ex-- change, areprovided; and purer.molassesandsugar,aswell as a separation of theimpurities as a separate byproduct are attained, by use of a specialresin which retains by adsorption within the resin the-low ion sucrosesolute while the highly ionized? solutes of themineral salts and'other'non sugar's are excluded.

Atypical cycle ofmy ionexclusion stage embodies;

(i)" The passing of a batch'ofmolasses throughan ion exclusion resin bedwhich is adsorbent of the sucrose solute soas to retain within thespecial porous resin struc 'ture of the bed, the sucrose solute whilethe high ion salts in solution, and other non-sugar materials, pass.through; I

(ii) Upon" and follo'win'gthemolasses, introducing water which removesthe sucrose solute from the. adsorbent' bed'asthewater passes throughthe bed;

.(iii) Recycling theinitial-portion of the efiiuent which issues justafter the water and sucrose solute begin to show in the efilue'nt, inorder to extract the impurities which'inthat portionare' higherproportionately than-in thesuccee'ding'portion;

(ii/)1 Fractionating theefiluent to collectthe-high purityportionthe're'of' separately from the mineral salt soluteand non-sugarcontaining liquor, so'that .thehigh purity portion can subsequently beseparately boiled and crystallized.

Although the procedurein dilferent sugar factories dif- 6r to continuousclarifiers 16 from which the clarified juice is drawn off. The sludge isdelivered to a vacuum filter 18 in which the remaining juice is mostlydrawn off and the mud cake sweetened off by application of a spray ofwater which lowers the sucrose content.

The clarified juice is generally of l415 Brix. it is delivered to asupply tank 20 (with the sweetened water from the vacuum filter, ifdesired) and then to a multiple elfect evaporator 22 in which it issubjected to a series of stages of boiling, each being at an increasingstage of vacuum. The finally concentrated liquor (termed syrup) at about60 to 70 Brix is held in supply tank 23. Subsequent concentration ofthis syrup involves the development of crystals in single effect cells24 (vacuum pans) in which exact control can be maintained under vacuumof 26.5 to 27.5 inches of mercury.

The mixture of crystals and mother liquor from the vacuum pan 24 isoptionally delivered to crystallizers 26 for further crystallization. Incentrifugals 28 the crystals are separated from the mother liquor of theresulting massecuite. The expelled liquid or A molasses is thendelivered to the B vacuum pan 30 for further concentration, alone orwith syrup from the supply tanks 23. The resulting mixture is treated inthe crystallizers 26; and the sugar crystals are separated from the Bmolasses in the centrifugal 28.

Clarification of the juiceafter heating and liming-is not, as a rule,highly efficient in the removal of insoluble material. Certainimpurities that are insoluble at this stage, including colloids andother substance of specific gravity closely approximating that of thesurrounding liquid, pass through into the clarified liquid. As the juicebecomes concentrated in its boiling in the evaporator into syrup, theunremoved insoluble impurities become more concentrated and they exertan effect adverse to crystal development and curing of the sugars. Thisadd especially to the difficulty of final-stage crystallization andlimits the practical end point of sugar recovery.

Moreover, during the process of concentration by boiling in both theevaporator and in the vacuum pans (the latter reducing the water contentof the massecuite to approximately five percent) there is usually aconsiderable additional precipitation of non-sugars and various forms ofimpurities.

As a result of these two sorts of impurities (precipitates andinsolubles) in the latter stage liquors, i. e., in the A" and B molasses(and because of the concentration of these impurities, especially in theB molasses) the usual procedure of boiling the B molasses in the vacuumpan involves excessive contamination and a relatively high degree ofviscosity. Such contamination and viscosity retards the boiling processand it also actually terminates crystal formation in the pan sooner thanthat which would be attainable in the absence of these impurities.

The steps preceding boiling the molasses in both the A and B stages arenot so seriously affected by the insoluble and precipitated impuritiesbecause, first, they are not in such concentrated form and, second, thepurities of the liquors and massecuites are much higher at this stageand can be handled and adequately cured in the centrifugal withouttrouble. Therefore, there is no special benefit, in the production ofraw sugar, in removing either the insoluble impurities or the solublemineral salts prior to the B molasses.

Besides the insoluble and precipitated impurities above referred to, athird kind of impurity, namely, mineral salts which are still insolution, exert a particularly serious retardment on the final stage ofcrystallization.

For the purpose of removing the soluble mineral salts and certain othernon-sugars, I employ an ion exclusion process after having clarified themolasses, as will now be described.

Referring to Fig. 2, the molasses is introduced into a mixing tank 40through pipe line 41 by operating valve 42. In this tank, the molassesis diluted to approximate carry-over of insoluble material.

1y 40-50 Brix. Either milk of lime (CaO) or suitably fired magnesiumoxide (MgO) is introduced through pipe line 43 by operating valve 44 soas to raise the pH to between 8.5-9.5 approximately. The mostadvantageous amount of alkalinity varies with the quality andcharacteristics of the liquor and the impurities to be dealt with.Phosphoric acid is then added through pipe 45 by operating valve 46 tothe extent of establishing a pH of 6.76.9. The temperature is raised byheating with steam coils 4-7 while the material is vigorously stirred bystirrers 48. The prepared liquor is dropped into receiving tank Where itis further stirred and where a flocculating aid is added, such as anorganic polyelectrolyte, for example, having the characteristics ofadding to precipitated fiocs and entraining the more finely suspendedmaterials such as colloids. The temperature is maintained or adjusted toF. in the tank which serves as supply tank for the clarifier or, in theembodiment illustrated, centrifugal separators.

In clarifying molasses solutions, excellent results are obtained by theuse of a solid bowl centrifugal separator 50 having a cylindrical bowlwith an imperforate side wall 51 and annular inturned flange 52, 53 atits top and bottom edges. At the bottom of the bowl there is an annularhood 54 having its outer edge inclined downwardly and close to the innerwall of the bowl. This hood is secured to the base of the bowl by aperforated annular plate 55. The hood and perforated plate serve touniformly distribute the incoming liquor and accelerate it to theapproximate peripheral speed directly adjacent to the inner surface ofthe bowl. In order to insure maintaining of high centrifugal forcethroughout the flow, an annular baflle plate 56 is secured close to theupper head. This plate 56 extends so that its outer edge is located atapproximately half of the depth of the material under treatment whilethe inner edge extends an inch nearer the axis than the surface of theliquor under treatment. The bowl, hood 54, plate 55 and baffle 56 areall rigidly aflixed to an axle or drive shaft 57 and are bal anced torotate without vibration.

The solid separator bowl is rotated to produce a force about 2,000 timesgravity or more and is preferably driven by an electric motor 58 througha fluid coupling 58c; but other driving means may be employed and othermethods of clutching or coupling may be used.

The solid separator bowl is operated at full speed and flow rate untilthe liquor outflow shows evidence of At that time inflow of liquor isshut off and water is introduced to remove the remaining liquor. As themachine is stopped the sludge is removed, preferably by a discharge plowsimilar to those used on sugar curing centrifugals. The clarified liquordischarges over the top flange 52 and passes down into the gutter 50gfrom whence it flows into a receiving tank (not shown) while the sludgeis dropped into a conveyor 59.

Since the sludges delivered into the scroll conveyor 59 contain aconsiderable amount of sucrose, they are delivered to the vacuum filter18 (Fig. 1) where, in carrying over the surface of the drum the sludgeis sweetened otf thorugh the application of a spray, or several sprays,which wash out the sucrose bearing liquor.

The clarified molasses is delivered to a supply tank 60 wherein itstemperature is adjusted to about 180 F. by a thermostat 62 controllingthe flow of steam in a line 64 connected with the tank.

The clarified molasses from the supply tank 60 of approximately 40 Brixand at a temperature of approximately 180 F. or higher is deliveredthrough a pipe 66, upon opening a control valve 68 therein, to a column70 containing a resin bed 72.

During passage of the molasses through the resin bed, the low polarsucrose solute is adsorbed and/or retained by the resin while the morehighly ionized weight in solution-is, 2.2,:eq uivalents, fi zrliter.

solutes, i. e., of. the. relatively. high pol'ar, position such asmineral salts. and: certain. non-sugars,- are, excluded by the resinsand pass on. with the, efiiuent?through. the pipe.74.uponopeningofvalves76 therein When it: appears that the. adsorbingcapacitywfthe bearing the low. ion sucrose liquor. This relatively nominal amountof intermediate. mixed. fractions; is recycled so. as. to; avoidsucrose. loss,, by opening; valvew82 in pipe line 84* returning;toytanlc 60.. When: the efiiuent appears clear enough the recyclingvalve782; is. closediand the valve. 86 in pipe 8.8 is; opened-. to;separately collect the demineralized liquor.

While severali types of: resin can' be: employcch. satisfactory results;have been obtained: in;- thezuse; of: a" high porosity, sulfonatedpolystyrene resim. ,crosselinked. at aboutd; and of 56-100. mesh.T-heslowr cross-linkage (indicating highporosity and adsorbing;capacity: of, resin matrix) is structurally selective;bywcontrol.of theamount ofdivinylbenzene"addedrpriorrto; sulfonation; 1

One example; of a resin. that; has beent. found suitable, but withoutlimitation of:the1inventiom thereto; isi sulfonated styrenedivinylbenzene copolymerizate, which has 1.8 sulfonic groups pen benzenering: The equivalent In conformity, with the requirementsof thisinventiomand the adsorption of. low polar sucrose solute, it, isessential .that resin porosity is provided adequate to accommodate. themolecular structure of sucrose. Otherresins having said properties maybe us'edi The amount ofrmolassestreated in each cycle is gaugedaccording. to, the. adsorbing. capacity: of the resin.- bed. Withconstant flow rate and predetermined amountxof water rinse for removalofthe. sucrose. solute: fromrthe resin bed, the cycles are accurately;timedand areaautotmatically controlled. Retaining resins stabilit-;-.-and functional effectiveness is accomplished by periodic-rinse ofthe resin with a salt (NaCl) solution from asupply tank 90 through pipeline 92 opening a valve 94 therein, while valves 68 and 79 are closed.The salt rinse is run-off through a separate outlet pipe 96. Since noion exchange takes place in the sense that applies to ion exchangeprocesses, no regenerants are required.-

Upon completion of the demineralization treatment, the density of thefinally treated liquor is somewhat low for direct introduction into avacuum pan for the final boiling and development of crystals. Therefore,arsmall multiple effect evaporator 97 is provided into which theclarified and demineralized liquor is delivered from the exclusion unit.This concentrates the liquor to a suitable density of about 80 Brix.

The clarified, demineralized, reconcentrated liquor is delivered to thevacuum pan supply tanks'98 which supply the C vacuum pan 99. Developmentof the crystals proceedsunder these conditions rapidly and to a greaterextent than is possible when the insoluble impurities and mineral saltsare present as in usual practice.

Among the principal advantages of the ion exclusion method of removingmineral salts and certain other nonsugars, from sugar solutions, ascompared to ion exchange are:

(a) More rapid, and greater frequency of, cycles and, therefore. lessequipment and lower cost. 1

(b) Simpler and easier control.

(1c), Elimination. of backwash: prior to regeneration, as required forion exchange.

(d) Greatly reduced dilution and, therefore, less evaporation required.

(a) Avoidance of' low pH: phases of cycles:and:associatedsusceptibilitytosucrose inversion;

(f) Elimination of requirement for cooling. Preferred temperatureduring-the. ion exclusioncycle. is at. least 1805-1851" FL -g) Noregenerants; required.

From the foregoing it will be understood that. because the sucrosesolute is adsorbed while: the impurities are excluded? by" the resin in:the: demineralization stage, I have'found it IIIOESt; practical andadvantageous'to' apply the demineralization stage. at that place or' tothose liquids in the manufacture of sugar wherethe percentageof'impuritiesperunitof volume is relatively high and the percentageofsugar content is relatively low. In cane sugar practice. thatpointiswreached-with the B molasses. Similarly, aflination liquorsacontaina relatively high percentage. of impurities. butzhave: highersugar content than B? molasses. An. equivalent point is reached in thefinal molasses inbeetsugar practice, despite-the fact that finalmolasses from beetscommonly has higher purity, i. e., contains moresugar than cane B molasses. The. greater sugar content; in" finalmolassesfrom beets is. due largely to the diificulty in handlingimpurities from beets. which are different innature fromcane impurities.

To. all: of; these, and'in fact toany-material, solution or liquorwhere' substantially equivalent limits andcon- ,ditions. of purity; andimpurities exist, my invention is applicable: to greatadvantage.

To further indicate the: value and importance of treating B'm0lassesand..the.like,.a contrast with known ion-exchange processes may bedrawn. In ion exchangers, the impurities arebroken downand drawn intothe type of: resintheres employed: The sugar? remains and passes on.Hence; a: liquor containing a. low percentage of" impurities: can more"readily. be treated, although other difficulties: may arise: due. totheamuclr larger volume which must be: handled and less' favorable"temperature conditions: and: pH values, especially in treating juices;

Although: my process" is especia'lly'aimed to. increase the yield-of1rawsugarifrom cane because thatis the basis. forsmoreyprofitableioperations by reduction of unit cost, other; important: results flowfrom the invention; The: resulting-molasses isspurerand canbe used inthe food industry" where; molasses heretofore has notbeen satisfactorybecause of the still-retained impurities. Also, certain bacterialimpurities are no longer present, providing a more sterile molasses andenabling the molasses to be stored longer Without spoiling. Furtherreduction in bacterial impurities can be accomplished by treating theclarified and demineralized molasses with ultra-violet light and usingsterile Water.

In addition, the impurities separated out in the excluded" liquor areuseful with food for cattle and poultry Where heretofore the wholemolasses at higher cost had to be used or further costly processing wasnecessary to extract the desired substances, vitamins and minerals.

Other indirect benefits of this process are evidenced by the completelyclean final crystallizer sugars, sometimes designated C or D sugars.Ordinarily these sugars are highly contaminated and are far too low ingrade and purity to be sold directly commercially. The

Another result is that crystallization, especially in the final stage,proceeds much more rapidly and further than is otherwise the case.

Again the final molasses instead of being the usual highly contaminatedblackstrap is, on the contrary, a-

clean food-grade product, high in vitamins and suitable as a foodcomponent.

Many modifications within the scope of the invention will occur to thoseskilled in the art. Therefore, the invention is not limited to theprecise form of the embodiment disclosed.

What is claimed is:

1. The process of clarifying and demineralizing B molasses, afiinationliquors and like sugar bearing solutions which contain a similarlycomparatively high percentage of impurities from previouscrystallization, comprising removing precipitated and insolubleimpurities to clarify the solution, subsequently passing the clarifiedsolution through a bed of low cross-linked high porosity highly ionizedresin having the property of adsorbing sugar and by ion-exclusionexcluding impurities, collecting the excluded-impurity-containingeifiuent, rinsing out the sugar by passing water through said resin bed,and collecting the sugar-bearing rinse separately for subsequentextraction of sugar, and maintaining the temperature during theion-exclusion stage and rising up to at least 180 F.

2. The process as claimed in claim 1 in which the solution is diluted toabout 40 to 50 Brix approximately, prior to clarification.

3. The process as claimed in claim 2 in which the clarificationcomprises adding basic and acidic reagents giving a resultant clarifiedsolution having a pH of about 6.76.9 approximately, adding afiocculating medium and removing the precipitated and insolublematerials.

4. The process as claimed in claim 3 in which the bed comprises a highporosity, highly ionized, sulfonated styrene divinylbenzenecopolymerizate resin.

5. The process as claimed in claim 1 in which the clarificationcomprises adding basic and acidic reagents giving a resultant clarifiedsolution having a pH of about 6.76.9 approximately, adding aflo-cculating medium and removing the precipitated and insolublematerials.

. 6. The process as claimed in claim 5 including collecting an initialsmall fraction of the sugar-bearing rinse, and recycling said smallfraction through said resin bed, and collecting the remainder of thesugar-bearing rinse separately for subsequent extraction of sugar.

7. The process as'claimed in claim 6 in which the bed comprises a"'highporosity, highly ionized, sulfonated styrene divinylbenzenecopolymerizate resin.

8. The process as'claimedin claim 1 in which the clarification comprisesadding basic and acidic reagents giving a resultant clarified solutionhaving a pH of about 6.7-6.9 approximately, adding a flocculating mediumand removingthe precipitated and insoluble materials, said resin bedcontaining a high porosity, highly ionized, sulfonated styrenedivinylbenzene copolymerizate resin.

9. The process of producing purified molasses from impure materials suchas B molasses, affination liquors and like sugar bearing solutions whichcontain a similarly comparatively high percentage of impurities fromprevious crystallization, comprising removing precipitated and insolubleimpurities to clarify said impure material, passing the said clarifiedimpure material through a bed of low cross-linked, high porosity, highlyionized resin having the property of adsorbing sugar and byion-exclusion excluding impurities, collecting theexcluded-impuritycontaining efiluent, rinsing out the sugar from theresin by passing water through said resin bed and collecting the sugarbearing rinse separately, and maintaining the temperature during the ionexclusion stage and rinsing up to at least F.

10. The process as claimed in claim 9 in which the bed comprises a highporosity, highly ionized, sulfonated styrene divinylbenzenecopolymerizate resin.

11. The process as claimed in claim 9 including subjecting the purifiedmolasses to ultra-violet light to sterilize said purified molasses.

References Cited in the file of this patent UNITED STATES PATENTS1,956,260 Wadsworth et al Apr. 24, 1934 2,388,194 Vallez Oct. 30, 19452,391,649 Shat'or Dec. 25, 1945 2,684,331 Bauman July 20, 1954 OTHERREFERENCES

1. THE PROCESS OF CLARIFYING AND DEMINERALIZING "B" MOLASSES, AFFINATIONLIQUORS AND LIKE SUGAR BEARING SOLUTIONS WHICH CONTAIN A SIMILARLYCOMPARATIVELY HIGH PERCENTAGE OF IMPURITIES FROM PREVIOUSCRYSTALLIZATION, COMPRISING REMOVING PRECIPITATED AND INSOLUBLEIMPURITIES TO CLARIFY THE SOLUTION, SUBSEQUENTLY PASSING THE CLARIFIEDSOLUTION THROUGH A BED OF LOW CROSS-LINKED HIGH POROSITY HIGHLY IONIZEDRESIN HAVING THE PROPERTY OF ADSORBING SUGAR AND BY ION-EXCLUSIONEXCLUDING IMPURITIES, COLLECTING THE EXCLUDED-IMPURITY-CONTAININGEFFUENT, RINSING OUT THE SUGAR BY PASSING WATER THROUGH SAID RESIN BED,AND COLLECTING THE SUGAR-BEARING FOR SUBSEQUENT EXTRACTION OF SUGAR, ANDMAINTAINING THE TEMPERATURE DURING THE ION-EXCLUSION STAGE AND RISING UPTO AT LEAST 180*F.